Serena Williams has long been celebrated as the number one women's tennis player in the whole world - and she's not letting a little thing like pregnancy hold her back.

The 35-year-old champion, who is currently expecting her first child with fiance Alexis Ohanian , took her huge bump to the tennis court today to keep up her practising - and she put everyone else to shame while doing so.

Dressed in black and white trainers, three-quarter-length black jogging bottoms and a gym top that encompassed her bump, Serena ran back and forth fielding serves from her tennis partner, in a video clip posted to her Instagram.

She showed off her famous backhand while returning every hit perfectly - and didn't even seem out of breath after the energetic session.

Serena's bump was on show during her practise session (Image: Serenawilliams/Instagram)

The expectant mum seemed to have unlimited energy (Image: Serenawilliams/Instagram)

Serena's fans couldn't believe how much energy she has for someone set to give birth later this summer, and took to Instagram to praise her.

"The baby will come out swinging! Awesome serena. Cant wait to see you back on the courts. We miss you," gushed one.

"And I can't even bend down during this pregnancy! you go girl," joked another.

The athlete is already looking forward to her comeback (Image: Serenawilliams/Instagram)

"QUEEN SLAYING HER WAY THROUGH 23 slams plus a baby! GOAT [greatest of all time]," wrote a third.

It comes after Serena donned a patriotic red, white and blue swimsuit for a recent Snapchat video, which perfectly packaged her growing bump.

The star has been keeping fans updated updated with a series of social media posts ever since she announced she was expecting her first child back in April.

In her Snapchat, Serena revealed that she bought the one-piece from high street store Target - for just $29.

Serena showed off her bump in this one-piece (Image: SerenaWilliams/snapchat)

She's been documenting her pregnancy on social media (Image: serenawilliams/Instagram)

"I went on a shopping spree at Target," Serena - who is worth an estimated $150m - told her Snapchat followers.

"Look, I mean it's the only place I could find a bathing suit that fit me."

Serena with her fiance Alexis (Image: serenawilliams/Instagram)

The pair are expecting their first child together later this year (Image: AFP)

Dropping another bombshell, the down to earth star also revealed she'd stopped by the dollar store earlier that day.

Serena recently confirmed that she and 33-year-old Alexis, who is the co-founder of Reddit, have decided not to find out their child’s sex beforehand.